Levels of organization in ecological systems

What is the lowest level of ecological organization?

Individuals form the lowest level of ecological organization.

• An individual is a single organism, such as one deer, one wolf, or one squirrel, living in a habitat.

What forms a population in ecology?

A population is formed when individuals of the same species interact with each other and combine. 

• For example, all the deer in a forest form a deer population.

What is a community? And what defines the boundaries of a community?

A community forms when populations of different species interact with each other.

• Communities don't have a specific, defined boundary. It can be small (like organisms in a patch of soil) or very large (like all plants and animals in a boreal forest).

What is an ecosystem?

An ecoystem is formed when communities interact with each other, and with other biotic, and abiotic processes.

• Ecosystems include both living and non-living components working together.

Example check: All the species in a pond (plants, insects, frogs, and fish) interacting together form what?

They form an aquatic community. Communities include all interacting species in a given area.

Define habitat.

A habitat is the physical space where an organism lives and carries out its daily activities. It can be thought of as the “address” of the organism. Multiple species may share the same habitat, though they use it differently.

Define ecological niche.

A niche is how an organism lives within its habitat — its “way of life.” It includes what the organism eats, how it reproduces, when it is active, where it shelters, and all the ways it interacts with its environment.

How can you remember the difference between a habitat and a niche?

A habitat is the address (where the organism lives), while a niche is the way of life (how the organism lives).

Give an example of multiple species sharing a habitat but having different niches.

Wolves, deer, moose, and squirrels may all live in the same northern Ontario forest habitat, but their niches differ:

• The wolf’s niche includes eating deer and moose, how it reproduces, and its role as a predator.

• The squirrel’s niche includes nesting in specific trees, eating seeds, and being active at certain times of day.